This invention relates to a mechanism for supplying in sequence unused regions of an analytical tape by predetermined length to an analytical section of an apparatus for biochemical analysis of a liquid sample. At the analytical section of the apparatus, the liquid sample is supplied onto the analytical tape, the applied sample is incubated, and the incubated sample is then subjected to photometric measurement for the desired analysis.
It is important for clinical chemical examination in the present medical treatment to quantitatively determine amounts of various analytes in body fluids (whole blood, plasma, serum, urine, saliva, etc.) so as to make accurate diagnosis and proper treatment. Moreover, a number of such clinical chemical examinations should be made rapidly. Accordingly, there are requirements in medical institutions and laboratories to provide methods and apparatus for carrying out the above quantitative analysis simply, automatically and continuously.
For the purpose of performing such quantitative analysis, biochemical analytical methods using a multilayer analytical element utilizing spectrophotometric measurement and an analytical element for measuring ion activity by the use of ion-selective electrodes have been proposed and put to practical use.
In the analysis using the multilayer analytical element (hereinafter sometimes referred to as colorimetric analytical element), a small amount of a liquid sample to be analyzed is applied (spotted) on the colorimetric analytical element and incubated at a given temperature for a given period of time to produce a color reaction between an analyte in the liquid and a reagent in the element, and then the analyte is quantitatively determined by measuring color density by spectrophotometry.
In the analysis using the analytical element by utilizing ion-selective electrodes, a liquid sample to be analyzed and a reference solution are applied onto each of ion-selective layers electrically separated from each other in the ion-selective electrodes and electrically connected to each other through a bridge, and a potential difference between the ion-selective electrodes is measured to determine the ion activity of the liquid sample.
To conduct automatically and continuously and analysis by using the analytical elements for biochemical analysis, it is convenient to use a long film (i.e., analytical tape) as disclosed in U.S. Pat. No. 3,526,480. It may be considered that the analytical tape (continuous tape) for biochemical analysis is wound up to form a roll, placed in a cassette and placed in a biochemical analyzer, and that a portion of the analytical tape having been used for analysis is wound up into a roll and placed in a cassette.
In performing the analysis, the analytical tape ought to be intermittently supplied to the analysis section of an analyzer by a given length. As the supply method, it can be considered that a roll shaft of the cassette for winding up the used portion of the analytical tape is intermittently rotated by a given number of rotations of the shaft or an angle of the shaft to move the analytical tape intermittently. In this method, however, the winding diameter of the roll for winding up the analytical tape is gradually changed with an increase of the amount of the wound-up film portion and the thickness of the film varies depending on the type of the tape. Accordingly, it is difficult to supply intermittently the analytical tape by a given length throughout a series of the analytical operations.